Chemestry sets are item drops that occur very rarely. Each set normally produces a Strange hat or weapon, but; There is the Rare occasion that a Chesestry set drops for a "COLLECTORS WEAPON" a "COLLECTORS WEAPON" is a chemestry set that once filled with 100 weapons, the set gives you a collectors version of that weaons. We obviously collect these things and are willing to help complete them, Mostly the Weapons versions... If you find a collectors set that You wouldn't like we happily accept it in Donations if you willing to donate.